Mounting and demounting of pulleys, gears, wheels, and like elements



A. VOEDISCH June 17, 1952 MOUNTING AND DEMOUNTING OF PULLEYS, GEARS, WHEELS, AND LIKE ELEMENTS Filed Jan. 20, 194'? INVENTOR. v fl-ed T/iedclsqk Patented June 17, 1952 MOUNTING AND DEMOUNTING OF'PULLEYS, GEARS, WHEELS, AND LIKE ELEMENTS A lied voed oh Wo er Mass" as i no t The llealdMachine Company, Worcester, Mass, a corporation of Massachusetts Application January 20, 194 17, Serial No. 723,118

6 Claims. 1

This invention re ates o impro emen s, sociated with a wheel, pulley, gear or similar torqueetransmittine el ent, y hi h to force such an element, w th h u mo t h onto a driving or driven shaft or spindle, and as readie 1y to overcomesoch tightness, in the operation of withdrawing or removing the element from the shaft. In conse ue e, of uch as w t dr l or r m val ope ation th is n n ed o r s to hammerin p in o h rhf e ped n that are liable to subject the parts to injury or strain.

i vention employ o the e p poses a ieren ial nu whose arr n em n a d oper o are such as to do: awayw th a l need fo p v i between shaft and element the usual spline, key or other equivalent connecti n at has he e oiore b en requir d for the operat n, in t is e vironment, of a differential nut. y in nt o provides the differential nut as a constituent and permanently connected pa t of the whee pul ey, gear or other torque-transmitting element, thus not only bviating the diifi ulty, al a s e e fore encountered in apply n a di erentia nu of sett n the second of the thread-engaging aciQn's started, but also eliminating the danger of stripp n -or mu ilati e t e th ds-i t e cou of such start n manipu a ion fi her and fu ther bj cts and advantages of my inven ion will be made app re t y t e to low ng detailed d s r p ion o sa e. en in on section with the a ompanying r n s in wh c F g.1 isaside clevation l ie showi a pul ey secu ed t a shaft in accordan e wi m i ntnn- Fig. 2 is an end view of the parts shown in Fi v3 is a sectional view, on line 3-45 of Fig. 2, showing the parts on a la ger sc .Elg dis a side elevational view showing a lock;-

ingzrin emolo db m entio Likegreference characters refer to like parts in thedifieren fig resl? drawin s o a i i 1 fi n h .I, which at one endis suitably tapered, asshown at 72 tor thereception thereonof any torque-trans- Inlttingor similar element, here shown as a pulley 3, wh se considerable attachment to said shaft sired. .For that purpose the ulley 3' for a V Por o o itsl n is t e bored, r ame or otherwise finished with an internal taper as shown at 4, to fit accurately on the tapered portion; of .shait I.

.cyondsa d t ered ortio the sha t h :a, redi cedsdi meter portion the end of which provides external screw threads 6 of relatively coarse pitch. The bore of pulley 3 (or other element to be attached to the shaft I) at the smaller and outer end of its tapered portion 4 is enlarged appreciably, as shown at l, by virtue of which is formed in said bore an annular shoulder 8 that serves, as hereinafter described, as an abutment for the end of a coil spring 9, the latter being received in said enlarged bore portion 7. The extreme outer end of bore enlargement 1 provides internal screw threads ll] of somewhat finer pitch, as shown, than the shaft threads 6, and inwardly of said threads ID the diameter of said bore portion 1 is still further increased by a shallow internal groove l l, whose outer wall forms an annular shoulder [2 at the inner end of the screw threads 10.

For cooperation with the external screw threads 6 of shaft l and the finer internal screw threads I0 of element 3, ,I provide a differential nut 13, having interior and exterior screw threads 6' and [0, respectively pitched to correspond to and to engage with the threads 6 on shaft l and the threads ID on element 3. When the nut I3 is screwed into the element 3, for assembling said parts together preparatory to their presentation as a unit to the shaft or spindle l, the inner end of said nut is adapted to press against the outer end of the aforesaid coil spring 9, whose other end seats against the shoulder 8; at a short distance from its inner end the not I 3 is formed with a circumferential groove I l of sufficient depth to completely receive a split expansible spring ring or washer l5 (see Fig. 4) upon the latters being contracted to a diameter smaller than its normal diameter. Said ring or washer l5 upon resumption of its normal diameter is adapted as shown in Fig. 3 to project into the shallow groove I l of bore enlargement 1, the said ring I 5 thus serving, when so positioned and allowed to expand to its normal diameter, as a look-- ing means to maintain the element 3, spring 9 and nut l3 in a permanently assembled relation.

That is to say, my invention contemplates the substantially permanent pie-assemblage with each pulley or other element 3, of its contained spring Sand its associated nut I 3 and locking ring I5, this assemblage being accomplished, after spring 9 is dropped into bore enlargement 1, by screwing the nut [3 (with ring I5 contracted by entry into threaded bore portion IE!) far enough into said threaded bore portion IQ, for said ring to pass the shoulder l2, whereupon said ring expands outwardly into bore groove H or element 3, and thereafter by its contact with shoulder 1-2,

outer circumference of locking ring I5 is prefer ably relieved at a number of places l6, [6 to permit said ring, in the above described operation of creating a permanent assembly of the parts to yield more freely in passing through the internal threads Ill of the element 3. 1

In the operation and use of my invention, the aforesaid permanent assembly (element 3, with its contained spring 9, locking ring I5 and nut 13) is moved inwardly on shaft l until the nut threads 6 engage the shaft threads 6; then the assembly is screwed inwardly as a unit by hand through the interaction of these matching thread portions, with no relative movement occurring at this time between element 3 and nut I3, because of the frictional pre-load imposed on the threads lll, I0 by spring 9. This screwing-in action, wholly on the threads 6 and 8', is continued until the tapered surfaces 4 and 2 are brought into firm contact; thereupon by a bar or pin (not shown) inserted in one of the radial holes I1, I! of element 3, and by a wrench (not shown) applied to the head I8 of nut l3, the operator produces an inward screwing of nut l3 on both sets of threads 6, 6' and l0, [0 at once; since the threads 6, 6' are more rapid in operation than the threads l0, l0, this relative turning between nut 13 and element 3 produces, differentially, a slow and therefore very powerful endwise inward thrust of element 3, to force its internal tapered surface 4 into the tightest possible binding engagement with the tapered portion 2 of shaft I, thus firmly uniting said parts for their desired rotation in unison.

In order to effect removal of the element 3 from the shaft I, the bar and wrench are engaged with said element and with the nut l3 respectively, as before, but this time are manipulated for an unscrewing action of the nut l3 on both sets of threads at once, so as to produce differentially a powerful force that moves the element 3 outwardly on the shaft, just enough to relieve the pressure of the taper bore .portion I against the tapered shaft section 2. Then, it is possible to remove the assembly as the unit from the shaft, by an unscrewing movement that simply involves travel of the nut threads 6 on the shaft threads 6.

Previous utilizations of a differential nut for the secure attachment of a wheel, gear, pulley or similar element to a shaft or spindle as typified by the disclosure of Bassett Patent No. 454,019, dated June 16, 1891, have always required the use of a key or spline between said shaft and said element in order to hold the element to an endwise movement during the differential action of the nut, and the presence of such a key has in turn prevented any pre-assembly temporary or permanent, of element and differential nut for their presentation as a unit, in initially threadedtogether engagement, to the shaft or spindle. In consequence of this, it has always been necessary, when using a differential nut in this environment, to apply the nut after the placement of the element on the shaft, the nut being initially screwed inwardly on the shaft threads and then with much difllculty caused to engage by its finer external threads with the internal threads of the already-positioned torque-transmitting or other element, which by the presence of the aforesaid key or spline, is not susceptible of being turned or manipulated on the shaft, to position its threads for the easy entrance of the nut threads. This difficulty, which exposes said finer threads to stripping and mutilation is entirely overcome by my invention, which allows the element and the differential nut to be presented to the shaft in alreadyassembled relation.

I make no claim to use of a differential nut in the manner shown and described by the aforesaid Bassett patent, but what I do claim and I desire to secure by Letters Patent is:

1. As a means of tightly attaching a wheel, pulley, gear or other torque-transmitting element to a shaft or spindle, a differential nut preassembled with said element, by interengaged screw threads of nut and element respectively, resilient means carried by said nut and operable in response to such pre-assembly for locking said element and said nut against dis-assembly, and spring means for creating a frictional resistance against relative turning between said parts on said first-mentioned threads, said nut having coarser screw threads adapted for interengagement, upon application of said assembly to said shaft, with corresponding shaft threads.

2. For the keyless attachment to a shaft or spindle, of a wheel, pulley, gear or other torquetransmitting element, a differential nut having internal screw threads adapted to be engaged with corresponding external threads on said shaft, said nut being presented to said shaft as a permanently-connected part of said element and in interengagement with said element by finer screw threads, and spring means for frictionally resisting relative turning movements between element and nut on their interengaged fine threads.

3. A torque-transmitting element bored for tight fit on a shaft or spindle, and having assembled therewith a differential nut having differently-pitched threads, the coarser threads adapted upon application of said assembly to said shaft to inter-engage with corresponding threads on said shaft and the finer nut threads, for said assembly being screwed into corresponding threads on said element, resilient means carried by said nut for locking said nut and said element in permanently assembled relation, and spring means for imposing a resistance to relative turning movement between element and nut on said finer threads.

4. The combination with a tapered shaft or spindle having a threaded outer end and a wheel pulley gear or other like element which is taper bored to fit said shaft, of a differential nut providing internal threads to screw onto said shaft threads, and having finer external threads by which to screw same into corresponding internal having a'tapered bore to fit said tapered shaft, and having beyond said tapered bore an internally threaded recess, said recess threads being of finer pitch than said shaft threads, a differential nut pre-assembled with said element and operable to force the tapered surfaces of element and shaft into close contact, said nut having internal threads for co-operation with said shaft threads and external threads for co-operation with said recess threads, and a spring seated in said recess, and put under compression by the screwing of said nut into said element, thereby to impose by said pre-assembly a frictional preload on the last-named co-operating threads.

6. The combination with a shaft having a tapered section and a threaded end beyond said taper, of a wheel, pulley, gear or like element having a tapered bore to fit said tapered shaft, and having beyond said tapered bore an internally threaded recess, said recess threads being of finer pitch than said shaft threads, a differential nut pre-assembled with said element and operable to force the tapered surfaces of element and shaft into close contact, said nut having internal threads for co-operation with said shaft REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 236,407 Anthony Jan. 11, 1881 385,798 Firth July 10, 1888 454,019 Bassett June 16, 1891 1,403,773 Hanson Jan. 17, 1922 1,437,471 Kirkham Dec. 5, 1922 1,604,690 Halaby Oct. 26, 1926 1,685,686 Smith Sept. 25, 1928 1,799,884 Chantry Apr. 7, 1931 

